With respect to light emitting elements such as LEDs, an increase in temperature lowers the optical output, varies the characteristics thereof and further adversely influences the service life thereof. Therefore, in a light source unit using light emitting elements, for example, LEDs and EL elements as a light source, it is necessary to prevent the temperature of the light emitting elements from rising for the purpose of improving the service life and various characteristics pertaining to efficiency.
Conventionally, as described in, for example, Japanese Laid-Open Patent Publication No. 2005-71821, such a lighting system has been known, in which a lighting device having LEDs as a light source is made so as to turn with respect to its supporting body to make the irradiation direction changeable and a concavo-convex shape for heat radiation is formed on the rear side of the main body.
However, although Japanese Laid-Open Patent Publication No. 2005-71821 shows a concavo-convex shape for heat radiation on the rear side of the main body, it does not show a detailed heat-radiating structure where the LEDs are used as a light source, and a concavo-convex shape for heat radiation is not associated with a change in the irradiation direction, that is, the direction of an elevation angle. Therefore, with the structure shown in Japanese Laid-Open Patent Publication No. 2005-71821, it is difficult to effectively prevent the temperature of the LEDs from rising.
The present invention has been developed in order to solve the above-described problems, and it is therefore an object of the invention to provide a lighting system capable of effectively preventing the temperature of a substrate, on which light emitting elements are disposed, from rising.